This invention pertains to a solar heat collector apparatus and method for use. It pertains particularly to a solar heating panel made principally of plastic materials and having a flexible inflatable cover, arranged to provide variable thermal performance and also prevent high stagnation temperatures which can cause thermal damage to the collector materials.
Solar heat collectors are well known in the patent art and have received renewed interest recently because of energy shortages and increasing energy costs. Early solar collectors or heating panels were constructed of rigid materials such as glass and metal tubing. Consequently, they were heavy and cumbersome to handle and install, and were also undesirably expensive to construct and to use. Non-rigid solar collectors constructed of plastic materials have been proposed recently, such as disclosed in U.S. Pat. No. 3,859,980 to Crawford, U.S. Pat. No. 4,036,209 to Press, U.S. Pat. No. 4,159,709 to Polazzetti and U.S. Pat. No. 4,160,443 to Brindle. However, these plastic solar panel designs do not protect the plastic materials from reaching excessive stagnation temperatures during inactive periods of panel operation when no fluid circulation occurs (stagnation mode). Also, these prior art panels do not provide a sufficient range of thermal efficiency during operation to cover all situations which could be encountered during normal usage. Thus a need clearly exists for a solar heating panel able to provide protection against thermal damage during stagnation mode, variable thermal performance as needed, convenient installation, and low cost.